Search found 736 matches

by eslapion
Tue Jun 18, 2019 9:22 am
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

Winbond W27C512 EPROM PLA I am not sure if this is displaying bus contentions or not. https://youtu.be/OORQERyNuw4 In order to know for sure if a glitch results in a bus contention results in a potential bus contention, you have to check it with a logic analyzer. The PLA is a sort of traffic light ...
by eslapion
Mon Jun 17, 2019 1:29 pm
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

I think even some of the early C64C's which had the long board may be unsuitable for a higher PROM with adapter. Yes, that's a problem there too. My solution was to solder the PROM directly onto a 28 pin DIP socket with rewiring, as I did with [url=http://www.amibay.com/showthread.php?81220-PLAkate...
by eslapion
Sun Jun 16, 2019 8:15 am
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

I was thinking could a similar solution be used on a C16/ plus4 ? http://www.vic20.de/Plus4.zip Just be careful with the Plus/4. The vertical space constraint is very tight in that machine as the metal plate of the bottom of the keyboard could easily touch a PLA substitute. The C16 has no such prob...
by eslapion
Sun Jun 16, 2019 3:47 am
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

Hey thanks for the comments! These cartridges and the ROM adapters holds 8 x 8kB ROM images. That is to say a 64kB EPROM . One needs to concatenate the 8 x 8kB files into 1 x 64kB file image to then be burnt on to the EPROM. At that point I had absolutely no idea what that meant or how do it. ... Oh...
by eslapion
Sat Jun 15, 2019 6:28 pm
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

Since most people try to fix faulty PROMs they try to use unsuccessfully as C64 PLAs by connecting a capacitor between the ground and the !CASRAM output, I thought it would be a good idea to show what's going on there. First, In case you don't already know, adding that capacitor doesn't do much good...
by eslapion
Sat Jun 15, 2019 3:51 pm
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

All this chatting about PLA PROMs gave me an appetite to check exactly what happens with the timing of the Ø0 CPU clock relative to !RAS, !CAS and !CASRAM. The result is this is the first time I check the behavior of the C64's DRAM access in such minute details. Stay tuned for very nice details and ...
by eslapion
Sat Jun 15, 2019 11:08 am
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

Here's what I suggest if you want to get the item you want. Communicate with the seller thru the "contact seller" button. Show him very clearly in pictures and/or describe what you want and NO deviation from that (I will put some pictures on this forum of what I purchased from the various sellers -...
by eslapion
Sat Jun 15, 2019 3:35 am
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

Oh! I'm getting confused with this photo you posted earlier.
DSCF4015.JPG
by eslapion
Sat Jun 15, 2019 2:37 am
Forum: Hardware
Topic: The Dos and Don'ts of using an EPROM as PLA in a C64.
Replies: 25
Views: 99

Re: The Dos and Don'ts of using an EPROM as PLA in a C64.

banman wrote:
Sat Jun 15, 2019 1:30 am
Here are some images of the knockoff (fake) ST M27C512-90B6 manufactured in KOREA.
I note the actual code etched on these chips is M27C512-90B1.
by eslapion
Thu Jun 13, 2019 4:02 pm
Forum: Hardware
Topic: Ray Carlsen power supplies and new web site
Replies: 0
Views: 56

Ray Carlsen power supplies and new web site

There is now a new, attractive, and well-organized front-end to Ray's website. Go to

http://carlsenelectronics.net

Ray has confirmed that he has lowered the prices on his power supplies, and his shipping costs are generally lower.